Q: Is it true that vegetable cooking oil has no cholesterol?

Dietary cholesterol is a kind of waxy substance which can only be found in animals and animal products but cannot be found in plants. It does not contribute energy which is different from dietary fats.

Food sources which are rich is dietary cholesterol are egg yolk, animal internal organs such as liver, lung, kidneys, sweetbread, etc. and also seafood such as pawns, squids, crab,  shellfish etc. Therefore, any vegetable cooking oil which is made from plant source( such as canola, sunflower, corn, soy bean, peanut, palm, or even coconut) do not contain cholesterol. In fact, there are different types of dietary fats found in the cooking oil which will greatly affect our blood cholesterol and eventually, our heart.

As we know, fats, which comprise fatty acids, are calorie-dense nutrients which contribute 9 kilocalories (kcal) per gram. They are essential for proper growth and development especially for children, because  they supply essential fatty acids for absorption and transportation of fat-soluble vitamins. They also act as food ingredients which affect the taste, consistency and stability of food products.

Q: I get very confused when food labels mention different types of fats. What is the different between saturate fat, monounsaturated fat and polyunsaturated fat? What is this new trans-fat we keep hearing about nowadays?

While some food labels may declare that they do not contain any cholesterol, it is crucial to scrutinise them to see if they do in  fact contain different types of fats.

Different types of fats can be found in our diet. Generally, they can be divided into the following categories:

(i) Saturated fats

Saturated fats (SFA) remain in solid form under room and chilled temperature. It is a kind of 'bad' fat which will increase our 'bad' cholesterol (LDL-C) level in the blood. This will eventually increase the risk of heart disease because of a blocked blood vessel. Food sources which are rich in saturated fats are butter, ghee, poultry skin from animal, palm oil, oil products such as condensed milk, non-diary  creamer, full cream, evaporated filled milk, coconut oil and coconut milk from plants.

(ii) Unsaturated fats

Unsaturated fats, commonly known as 'good' fats, is subdivided into mono- and poly-unsaturated fats.

(a) Monounsaturated fats (MUFA) remains in liquid form under room temperature and but it becomes solid at chilled temperature. By replacing the saturated fats in our diet, MUFA will lower our 'bad' cholesterol in the blood and reduce the risk of heart disease. Food sources which are rich in MUFA include cooking oil made from canola, olive and pure peanut.

(b) Polyunsaturated fats (PUFA)  remains in liquid form under room and chilled temperature. It will help to lower high-triglyceride level in the blood and it has blood vessel dilating properties which reduce the risk of heart disease. Food sources which are rich in PUFA include cooking oil made from corn, sunflower and sot bean from plants; and omega-3 from oily fish.

(iii) Trans-fats

Trans-fat are a kind of fat formed from the hydrogenation process ("adding hydrogen"} This process helps to increase the shelf life of food products. Therefore, another term for 'trans-fats' is 'hydrogenated fats'. Trans-fats are also another kind of 'bad' fats which will increase our 'bad' cholesterol level and reduce our 'good' cholesterol level. Food sources which are rich in trans-fat include hydrogenated margarine, bakery products, candies, chocolate, and cookies.

This issue's resident dietitian is  Mr For Wei Chek, Dietitian of National Healthcare Group Polyclinics (NHGP) . Email your questions for Dear Dietitian to dmlife@diabetes.org.sg or fax the questions addressed to the Editor, Diabetes Singapore, Diabetic Society of Singapore Fax 6553 1801